The present invention relates to fastener applying equipment, and more particularly to nailers for the application of roofing fasteners.
Roofs for commercial or industrial buildings typically are flat and cover a significant area. Two preferred materials for constructing the substructure of large flat roofs, or the xe2x80x9cdeck,xe2x80x9d are steel and wood. Steel is preferred in regions of the country subject to significant snow accumulation because of its strength and ability to withstand snow loads. Wood is preferred in regions with little or no snow accumulation, and possibly where structures may be subject to significant vibration during earthquakes. Wood is able to flex under such vibration without breaking or permanently deforming.
Wood deck roofs are typically weather-proofed to keep out the elements. To do so, the deck is covered with multiple layers of xe2x80x9cfeltxe2x80x9d (i.e., a thin sheet of water-impervious material), asphalt and sealer. This type of roof is called a built-up roof, or xe2x80x9cBUR.xe2x80x9d In constructing a BUR, felt is first secured to the wood deck and then multiple layers of tar and asphalt are laid over the felt. The exact number of layers depends on the architect""s (building owner""s) specification or local building code specifications.
To secure felt to the wood deck, fasteners, such as staples or nails, are driven through the felt into the wood. In many regions of the country, building codes require the felt to be fastened regular intervals, for example, every 9 or 18 inches. The intervals depend on whether one sheet of felt is fastened directly to the deck or whether two overlapping sheets of felt are fastened to the deck along a seam. The number of fasteners required for a single roof may range from 1 to 5 million, depending on the size of the roof and the specifications.
Conventionally, fasteners are driven through the felt and into the wood deck in one of two ways. In one way, roofing nails are manually driven through the felt and into the deck. This method becomes costly because it requires many man-hours to drive millions of nails.
In the other way, a device called a xe2x80x9cbase tape staplerxe2x80x9d is used. The base tape stapler unrolls a strip of tape over the felt and drives staples into the wood deck, straddling the tape, at regular intervals. FIG. 1 shows a base tape stapler 10 including a pneumatic stapler 11 mounted on a frame 12 with rollers 14. The base tape 6 is wrapped on a spool of tape 7 and guided toward the stapler 10 within slot guides 16. The base tape stapler also includes an actuator system 20 that includes a roller 14a having a bolt 22 that regularly engages a switch 24 as the roller rotates and the bolt 22 bumps the switch.
In operation, the base tape 6 must be threaded though guide slots 16 and initially stapled or held against the deck in starter region 2a with multiple staples. This is to provide a fixed end of the base tape 6 so that as the base tape stapler 10 is pushed away from the starter region 2a, the supply of tape 7 is unrolled and fed through slot guides 16, under the staple barrel 13, which includes a driving blade (not shown). As the roller 14a rotates, the bolt 22 engages the switch 24 causing stapler 11 to drive the driving blade downward to engage and drive staples at regular intervals through the felt 4, into the wood deck 8, straddling the base tape 6, and pressing it down against the felt 4. As a result, the felt under the base tape between adjacent staples is held down by the base tape to increase the holding area of the staples.
Although base tape staplers provide a way to fasten felt to a large wood deck, they suffer several shortcomings. First, base tape staplers easily drive staples into conventional, multi-layer plywood decks, but they fail to drive staples well into newer, more dense, wood decks constructed from OSB board. Accordingly, the holding power of the staples is diminished because they are not driven very far into the OSB.
Second, it is imperative that the base tape stapler avoid contacting and nicking the base tape with driven staples to prevent tears in the tape. However, this objective is rarely met if the deck is uneven because the stapler becomes tilted and shoots staples at an angle toward the base tape, and usually directly into the base tape. Thus, in many cases the base tape stapler must be stopped and the tape restarted so that it is properly laid. This results in costly down time.
Third, the base tape must be pulled through the guides of the stapler by first securing the tape to the deck. This delays start-up time and thus operating time for the base tape stapler.
Fourth, the base tape stapler only lays tape in straight lines. To turn the stapler and begin laying tape in another direction, the tape must be severed, the machine turned in the new direction, and the base tape secured again to the deck in another starter region.
Fifth, the driver blades of the base tape stapler frequently break due to the significant forces required to drive staples. Replacement of the blade reduces operating time and increases operating costs.
Finally, voids are created under the tape between staples when the next layer of the BUR is applied over the felt because nothing holds the tape tightly against the felt in the areas between the staples. With these voids, any movement in the layers above the felt layer due to heat expansion or cold contraction may cause movement between the built-up layers and the felt. This movement may cause the felt to tear. Furthermore, moisture may be captured in the voids between the tape and felt, which can lead to decay of the felt and/or underlying wood deck.
The aforementioned problems are overcome in the present invention in which a walk-behind rolling nailer drives nails through fastener caps at regular intervals.
In a first aspect of the invention, the fastening system includes a wheeled chassis, a nail gun, an actuator system, and a fastener cap dispenser. The nail gun is mounted on the chassis, which includes rollers and an actuating wheel. A mechanism for communicating with the actuator system at regular intervals is mounted on the actuating wheel. This mechanism may include, for example, bumps, recesses, photo detectable elements, laser detectable elements, machine readable code, or the like. The actuator system includes an actuator aligned with the mechanism and in communication with the nail gun. The actuator is capable of sensing or communicating with the mechanism. As the wheel rotates, the mechanism engages the actuator to fire the nail gun. The actuator system also actuates the fastener cap dispenser, so that as the nail gun fires a fastener through one fastener cap, the dispenser dispenses another fastener cap in the driving path of the nail gun.
In a first variation of the first aspect, the fastener caps are sequentially arranged, or collated, on a strip of material and the fastener cap dispenser system is configured to feed the fastener caps. To do so, the fastener cap dispenser includes a reciprocating xe2x80x9cpickerxe2x80x9d including four teeth that simultaneously engage and advance two sequential fastener caps on the collated strip of fastener caps toward the drive path of the nail gun. Preferably, two of the four teeth engage opposite sides of one fastener cap and the other two teeth engage opposite sides of another fastener cap. The picker may also include one or more anti-backup teeth or devices to prevent the collated fastener caps from backing-up as it reciprocates.
In a second variation of the first aspect, the wheel includes several mechanisms for communicating with the actuator system, and the actuator system includes several corresponding actuators, as well as a control system. The additional mechanisms are positioned at different regular intervals on the wheel. With the control system, the user can select different intervals at which he wants to drive fasteners as the fastening system is moved.
In a third variation of the first aspect, the control system is operable in either an automatic mode, wherein the fastening system discharges nails automatically at the regular intervals, or a manual mode, where the user may manually fire the nail gun.
In a second aspect of the invention, the fastening system includes an accumulator that prevents excess fastener caps from being fed too quickly to the dispenser and jamming it. The accumulator is positioned downstream from a spool of fastener caps, and upstream of the dispenser. A strip of fastener caps drapes across the accumulator. If the spool unwinds too quickly, the accumulator prevents advancement of excess caps toward the dispenser. The excess caps are temporarily stored in the accumulator.
In a third aspect of the invention, the nail gun is outfitted with an exhaust shield that deflects exhaust air from the nail gun, away from the other components of the fastening system so that oil, typically included in such exhaust air, does not contaminate those components.
The fastening system of the invention offers many benefits. First, it provides a quick and efficient way to fasten roofing or other material to a large deck by driving independent fasteners through associated fastening caps and into the deck. With the relatively small size of fastening caps, the number of voids between the fastener and the secured material is minimized.
Second, with the independence of each dispensed fastener/fastening cap unit, or xe2x80x9cfastening unit,xe2x80x9d fastening felt down is initiated simply by rolling the fastening system or actuating it in manual mode. Moreover, the fastening units allow a user to turn the fastening system without stopping.
Third, with the picker of the fastening system, fastener caps may be fed at high speeds with minimal jamming in the picker due to the multiple contact points on multiple fastener caps.
Fourth, the accumulator bin prevents fastener caps from jamming in the picker.
Fifth, the fastening system offers users the option of selecting between different fastener discharge intervals, as well as operation between an automatic nailing mode and a manual nailing mode on the fly.
These and other objects, advantages and features of the invention will be more readily understood and appreciated by reference to the detailed description of the preferred embodiments and the drawings.